Flow-through oxygenator

ABSTRACT

An oxygen emitter which is an electrolytic cell is disclosed. When the anode and cathode are separated by a critical distance, very small microbubbles and nanobubbles of oxygen are generated. The very small oxygen bubbles remain in suspension, forming a solution supersaturated in oxygen. A flow-through model for oxygenating flowing water is disclosed. The use of supersaturated water for enhancing the growth of plants is disclosed. Methods for applying supersaturated water to plants manually, by drip irrigation or in hydroponic culture are described. The treatment of waste water by raising the dissolved oxygen with the use of an oxygen emitter is disclosed.

RELATED APPLICATIONS

This application is a division of application Ser. No. 10/732,326 filedDec. 10, 2003, which in turn is a continuation-in-part of applicationSer. No. 10/372,017, filed Feb. 21, 2003, now U.S. Pat. No. 6,689,262,which claims the benefit of U.S. Provisional Application No. 60/358,534,filed Feb. 22, 2002, each of which is hereby fully incorporated hereinby reference.

FIELD OF THE INVENTION

This invention relates to the electrolytic generation of microbubbles ofoxygen for increasing the oxygen content of flowing water. Thisinvention also relates to the use of superoxygenated water to enhancethe growth and yield of plants. The flow-through model is useful foroxygenating water for hydroponic plant culture, drip irrigation andwaste water treatment.

BACKGROUND OF THE INVENTION

Many benefits may be obtained through raising the oxygen content ofaqueous media. Efforts have been made to achieve higher saturated orsupersaturated oxygen levels for applications such as the improvement ofwater quality in ponds, lakes, marshes and reservoirs, thedetoxification of contaminated water, culture of fish, shrimp and otheraquatic animals, biological culture and hydroponic culture. For example,fish held in a limited environment such as an aquarium, a bait bucket ora live hold tank may quickly use up the dissolved oxygen in the courseof normal respiration and are then subject to hypoxic stress, which canlead to death. A similar effect is seen in cell cultures, where therespiring cells would benefit from higher oxygen content of the medium.Organic pollutants from agricultural, municipal and industrialfacilities spread through the ground and surface water and adverselyaffect life forms. Many pollutants are toxic, carcinogenic or mutagenic.Decomposition of these pollutants is facilitated by oxygen, both bydirect chemical detoxifying reactions or by stimulating the growth ofdetoxifying microflora. Contaminated water is described as having anincreased biological oxygen demand (BOD) and water treatment is aimed atdecreasing the BOD so as to make more oxygen available for fish andother life forms.

The most common method of increasing the oxygen content of a medium isby sparging with air or oxygen. While this is a simple method, theresulting large bubbles produced simply break the surface and aredischarged into the atmosphere. Attempts have been made to reduce thesize of the bubbles in order to facilitate oxygen transfer by increasingthe total surface area of the oxygen bubbles. U.S. Pat. No. 5,534,143discloses a microbubble generator that achieves a bubble size of about0.10 millimeters to about 3 millimeters in diameter. U.S. Pat. No.6,394,429 (“the '429 patent”) discloses a device for producingmicrobubbles, ranging in size from 0.1 to 100 microns in diameter, byforcing air into the fluid at high pressure through a small orifice.

When the object of generating bubbles is to oxygenate the water, eitherair, with an oxygen content of about 21%, or pure oxygen may be used.The production of oxygen and hydrogen by the electrolysis of water iswell known. A current is applied across an anode and a cathode which areimmersed in an aqueous medium. The current may be a direct current froma battery or an AC/DC converter from a line. Hydrogen gas is produced atthe cathode and oxygen gas is produced at the anode. The reactions are:

AT THE CATHODE: 4H₂O + 4e⁻ → 4OH⁻ + 2H₂ AT THE ANODE: 2H₂O → O₂ + 4H⁺ +4e⁻ NET REACTION: 6H₂O → 4OH⁻ + 4H⁺ ++ 2H₂ + O₂286 kilojoules of energy is required to generate one mole of oxygen.

The gasses form bubbles which rise to the surface of the fluid and maybe collected. Either the oxygen or the hydrogen may be collected forvarious uses. The “electrolytic water” surrounding the anode becomesacidic while the electrolytic water surrounding the cathode becomesbasic. Therefore, the electrodes tend to foul or pit and have a limitedlife in these corrosive environments.

Many cathodes and anodes are commercially available. U.S. Pat. No.5,982,609 discloses cathodes comprising a metal or metallic oxide of atleast one metal selected from the group consisting of ruthenium,iridium, nickel, iron, rhodium, rhenium, cobalt, tungsten, manganese,tantalum, molybdenum, lead, titanium, platinum, palladium and osmium.Anodes are formed from the same metallic oxides or metals as cathodes.Electrodes may also be formed from alloys of the above metals or metalsand oxides co-deposited on a substrate. The cathode and anodes may beformed on any convenient support in any desired shape or size. It ispossible to use the same materials or different materials for bothelectrodes. The choice is determined according to the uses. Platinum andiron alloys (“stainless steel”) are often preferred materials due totheir inherent resistance to the corrosive electrolytic water. Anespecially preferred anode disclosed in U.S. Pat. No. 4,252,856comprises vacuum deposited iridium oxide.

Holding vessels for live animals generally have a high population ofanimals which use up the available oxygen rapidly. Pumps to supplyoxygen have high power requirements and the noise and bubbling mayfurther stress the animals. The available electrolytic generatorslikewise have high power requirements and additionally run at highvoltages and produce acidic and basic water which are detrimental tolive animals. Many of the uses of oxygenators, such as keeping bait orcaught fish alive, would benefit from portable devices that did notrequire a source of high power. The need remains for quiet, portable,low voltage means to oxygenate water.

It has also been known that plant roots are healthier when oxygenatedwater is applied. It is thought that oxygen inhibits the growth ofdeleterious fungi. The water sparged with air as in the '429 patent wasshown to increase the biomass of hydroponically grown cucumbers andtomatoes by about 15%.

The need remains for oxygenator models suitable to be placed in-line inwater distribution devices so as to be applied to field as well ashydroponic culture.

SUMMARY OF THE INVENTION

This invention provides an oxygen emitter which is an electrolytic cellwhich generates very small microbubbles and nanobubbles of oxygen in anaqueous medium, which bubbles are too small to break the surface tensionof the medium, resulting in a medium supersaturated with oxygen.

The electrodes may be a metal or oxide of at least one metal selectedfrom the group consisting of ruthenium, iridium, nickel, iron, rhodium,rhenium, cobalt, tungsten, manganese, tantalum, molybdenum, lead,titanium, platinum, palladium and osmium or oxides thereof. Theelectrodes may be formed into open grids or may be closed surfaces. Themost preferred cathode is a stainless steel mesh. The most preferredmesh is a 1/16 inch grid. The most preferred anode is platinum andiridium oxide on a support. A preferred support is titanium.

In order to form microbubbles and nanobubbles, the anode and cathode areseparated by a critical distance. The critical distance ranges from0.005 inches to 0.140 inches. The preferred critical distance is from0.045 to 0.060 inches.

Models of different size are provided to be applicable to variousvolumes of aqueous medium to be oxygenated. The public is directed tochoose the applicable model based on volume and power requirements ofprojected use. Those models with low voltage requirements are especiallysuited to oxygenating water in which animals are to be held.

Controls are provided to regulate the current and timing ofelectrolysis.

A flow-through model is provided which may be connected in-line to awatering hose or to a hydroponic circulating system. The flow-throughmodel can be formed into a tube with triangular cross-section. In thismodel, the anode is placed toward the outside of the tube and thecathode is placed on the inside, contacting the water flow.Alternatively, the anodes and cathodes may be in plates parallel to thelong axis of the tube, or may be plates in a wafer stack. Alternately,the electrodes may be placed in a side tube (“T” model) out of thedirect flow of water. Protocols are provided to produce superoxygenatedwater at the desired flow rate and at the desired power usage. Controlsare inserted to activate electrolysis when water is flowing anddeactivate electrolysis at rest.

This invention includes a method to promote growth and increase yield ofplants by application of superoxygenated water. The water treated withthe emitter of this invention is one example of superoxygenated water.Plants may be grown in hydroponic culture or in soil. The use of theflow-through model for drip irrigation of crops and waste watertreatment is disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the O₂ emitter of the invention.

FIG. 2 is an assembled device.

FIG. 3 is a diagram of the electronic controls of the O₂ emitter.

FIG. 4 shows a funnel or pyramid variation of the O₂ emitter.

FIG. 5 shows a multilayer sandwich O₂ emitter.

FIG. 6 shows the yield of tomato plants watered with superoxygenatedwater.

FIG. 7 shows an oxygenation chamber suitable for flow-throughapplications. FIG. 7A is a cross section showing arrangement of threeplate electrodes. FIG. 7B is a longitudinal section showing the pointsof connection to the power source.

FIG. 8 is a graph showing the oxygenation of waste water.

DETAILED DESCRIPTION OF THE INVENTION Definitions

For the purpose of describing the present invention, the following termshave these meanings:

“Critical distance” means the distance separating the anode and cathodeat which evolved oxygen forms microbubbles and nanobubbles.

“Critical distance” means the distance separating the anode and cathodeat which evolved oxygen forms microbubbles and nanobubbles.

“O₂ emitter” means a cell comprised of at least one anode and at leastone cathode separated by the critical distance.

“Metal” means a metal or an alloy of one or more metals.

“Microbubble” means a bubble with a diameter less than 50 microns.

“Nanobubble” means a bubble with a diameter less than that necessary tobreak the surface tension of water. Nanobubbles remain suspended in thewater, giving the water an opalescent or milky appearance.

“Supersaturated” means oxygen at a higher concentration than normalcalculated oxygen solubility at a particular temperature and pressure.

“Superoxygenated water” means water with an oxygen content at least 120%of that calculated to be saturated at a temperature.

“Water” means any aqueous medium with resistance less than one ohm persquare centimeter; that is, a medium that can support the electrolysisof water. In general, the lower limit of resistance for a medium thatcan support electrolysis is water containing more than 2000 ppm totaldissolved solids.

The present invention produces microbubbles and nanobubbles of oxygenvia the electrolysis of water. As molecular oxygen radical (atomicweight 8) is produced, it reacts to form molecular oxygen, O₂. In thespecial dimensions of the invention, as explained in more detail in thefollowing examples, O₂ forms bubbles which are too small to break thesurface tension of the fluid. These bubbles remain suspendedindefinitely in the fluid and, when allowed to build up, make the fluidopalescent or milky. Only after several hours do the bubbles begin tocoalesce on the sides of the container and the water clears. During thattime, the water is supersaturated with oxygen. In contrast, the H₂formed readily coalesces into larger bubbles which are discharged intothe atmosphere, as can be seen by bubble formation at the cathode.

The first objective of this invention was to make an oxygen emitter withlow power demands, low voltage and low current for use with liveanimals. For that reason, a small button emitter was devised. The anodeand cathode were set at varying distances. It was found thatelectrolysis took place at very short distances before arcing of thecurrent occurred. Surprisingly, at slightly larger distances, the waterbecame milky and no bubbles formed at the anode, while hydrogencontinued to be bubbled off the cathode. At distance of 0.140 inchesbetween the anode and cathode, it was observed that the oxygen formedbubbles at the anode. Therefore, the critical distance for microbubbleand nanobubble formation was determined to be between 0.005 inches and0.140 inches.

EXAMPLE 1 Oxygen Emitter

As shown in FIG. 1, the oxygen evolving anode 1 selected as the mostefficient is an iridium oxide coated single sided sheet of platinum on asupport of titanium (Eltech, Fairport Harbor, Ohio). The cathode 2 is a(fraction ( 1/16)} inch mesh (size 8 mesh) marine stainless steelscreen. The anode and cathode are separated by a non-conducting spacer 3containing a gap 4 for the passage of gas and mixing of anodic andcathodic water and connected to a power source through a connectionpoint 5. FIG. 2 shows a plan view of the assembled device. The O₂emitter 6 with the anode connecting wire 7 and the cathode connectingwire 8 is contained in an enclosure 9, connected to the batterycompartment 10. The spacer thickness is critical as it sets the criticaldistance. It must be of sufficient thickness to prevent arcing of thecurrent, but thin enough to separate the electrodes by no more than0.140 inches. Above that thickness, the power needs are higher and theoxygen bubbles formed at higher voltage will coalesce and escape thefluid. Preferably, the spacer is from 0.005 to 0.075 inches thick. Atthe lower limits, the emitter tends to foul more quickly. Mostpreferably, the spacer is about 0.050 inches thick. The spacer may beany nonconductive material such as nylon, fiberglass, Teflon®, polymeror other plastic. Because of the criticality of the space distance, itis preferable to have a non-compressible spacer. It was found that Buna,with a durometer measure of 60 was not acceptable due to decomposition.Viton, a common fluoroelastomer, has a durometer measure of 90 and wasfound to hold its shape well.

In operation, a small device with an O₂ emitter 1.485 inches in diameterwas driven by 4AA batteries. The critical distance was held at 0.050inches with a Viton spacer. Five gallons of water became saturated inseven minutes. This size is suitable for raising oxygen levels in anaquarium or bait bucket.

It is convenient to attach a control circuit which comprises a timerthat is thermostatically controlled by a temperature sensor whichdetermines the off time for the cathode. When the temperature of thesolution changes, the resistance of the thermistor changes, which causesan off time of a certain duration. In cool water, the duration is longerso in a given volume, the emitter generates less oxygen. When the wateris warmer and therefore hold less oxygen, the duration of off time isshorter. Thus the device is self-controlled to use power mosteconomically. FIG. 3 shows a block diagram of a timer control with anode1, cathode 2, thermistor temperature sensor 3, timer control circuit 4and wire from a direct current power source 5.

EXAMPLE 2 Measurement of O₂ Bubbles

Attempts were made to measure the diameter of the O₂ bubbles emitted bythe device of Example 1. In the case of particles other than gasses,measurements can easily be made by scanning electron microscopy, butgasses do not survive electron microscopy. Large bubble may be measuredby pore exclusion, for example, which is also not feasible whenmeasuring a gas bubble. A black and white digital, high contrast,backlit photograph of treated water with a millimeter scale referencewas shot of water produced by the emitter of Example 1. About 125bubbles were seen in the area selected for measurement. Seven bubblesranging from the smallest clearly seen to the largest were measured. Thearea was enlarged, giving a scale multiplier of 0.029412.

Recorded bubble diameters at scale were 0.16, 0.22, 0.35, 0.51, 0.76,0.88 and 1.09 millimeters. The last three were considered outliers byreverse analysis of variance and were assumed to be hydrogen bubbles.When multiplied by the scale multiplier, the assumed O₂ bubbles werefound to range from 4.7 to 15 microns in diameter. This test was limitedby the resolution of the camera and smaller bubbles in the nanometerrange could not be resolved. It is known that white light cannot resolvefeatures in the nanometer size range, so monochromatic laser light maygive resolution sensitive enough to measure smaller bubbles. Effortscontinue to increase the sensitivity of measurement so that sub-microndiameter bubbles can be measured.

EXAMPLE 3 Other Models of Oxygen Emitter

Depending on the volume of fluid to be oxygenated, the oxygen emitter ofthis invention may be shaped as a circle, rectangle, cone or othermodel. One or more may be set in a substrate that may be metal, glass,plastic or other material. The substrate is not critical as long as thecurrent is isolated to the electrodes by the nonconductor spacermaterial of a thickness from 0.005 to 0.075 inches, preferably 0.050inches. It has been noticed that the flow of water seems to be at theperiphery of the emitter, while the evolved visible bubbles (H₂) ariseat the center of the emitter. Therefore, a funnel or pyramidal shapedemitter was constructed to treat larger volumes of fluid. FIG. 4 is across sectional diagram of such an emitter. The anode 1 is formed as anopen grid separated from a marine grade stainless steel screen cathode 2by the critical distance by spacer 3 around the periphery of the emitterand at the apex. This flow-through embodiment is suitable for treatinglarge volumes of water rapidly.

The size may be varied as required. A round emitter for oxygenating abait bucket may be about 2 inches in diameter, while a 3-inch diameteremitter is adequate for oxygenating a 10 to 40 gallon tank. The livewell of a fishing boat will generally hold 40 to 80 gallons of water andrequire a 4-inch diameter emitter. It is within the scope of thisinvention to construct larger emitters or to use several in a series tooxygenate larger volumes. It is also within the scope of this inventionto vary the model to provide for low voltage and amperage in cases wherethe need for oxygen is moderate and long lasting or conversely, tosupersaturate water very quickly at higher voltage and amperage. In thespecial dimensions of the present invention, it has been found that a 6volt battery supplying a current as low as 40 milliamperes is sufficientto generate oxygen. Such a model is especially useful with live plantsor animals, while it is more convenient for industrial use to use ahigher voltage and current. Table I shows a number of models suitable tovarious uses.

TABLE I Emitter Model Gallons Volts Amps Max. Ave Watts Bait keeper 5 60.090 0.060 0.36 Livewell 32 12 0.180 0.120 1.44 OEM 2 inch 10 12 0.2100.120 1.44 Bait store 70 12 0.180 0.180 2.16 Double cycle 2 12 0.1800.180 2.16 OEM 3 inch 50 12 0.500 0.265 3.48 OEM 4 inch 80 12 0.9800.410 4.92 Water pail 2 24 1.200 1.200 28.80 Plate 250 12 5.000 2.50030.00

EXAMPLE 4 Multilayer Sandwich O₂ Emitter

An O₂ emitter was made in a multilayer sandwich embodiment. (FIG. 5) Aniridium oxide coated platinum anode 1 was formed into a grid to allowgood water flow and sandwiched between two stainless steel screencathodes 2. Spacing was held at the critical distance by nylon spacers3. The embodiment illustrated is held in a cassette 4 which is securedby nylon bolt 5 with a nylon washer 6. The dimensions selected were:

cathode screen 0.045 inches thick nylon spacer 0.053 inches thick anodegrid 0.035 inches thick nylon spacer 0.053 inches thick cathode screen0.045 inches thick,for an overall emitter thickness of 0.231 inches thick inches.

If a more powerful emitter is desired, it is within the scope of thisinvention to repeat the sequence of stacking. For example, an embodimentmay easily be constructed with this sequence: cathode, spacer, anode,spacer, cathode, spacer, anode, spacer, cathode, spacer, anode, spacer,cathode. The number of layers in the sandwich is limited only by thepower requirements acceptable for an application.

EXAMPLE 5 Effect of Superoxygenated Water on the Growth of Plants

It is known that oxygen is important for the growth of plants. Althoughplants evolve oxygen during photosynthesis, they also have a requirementfor oxygen for respiration. Oxygen is evolved in the leaves of theplants, while often the roots are in a hypoxic environment withoutenough oxygen to support optimum respiration, which can be reflected inless than optimum growth and nutrient utilization. Hydroponically grownplants are particularly susceptible to oxygen deficit in the rootsystem. U.S. Pat. No. 5,887,383 describes a liquid supply pump unit forhydroponic cultures which attain oxygen enrichment by sparging with air.Such a method has high energy requirements and is noisy. Furthermore,while suitable for self-contained hydroponic culture, the apparatus isnot usable for field irrigation. In a report available on the web, itwas shown that hydroponically grown cucumbers and tomatoes supplied withwater oxygenated with a device similar to that described in the '429patent had increased biomass of about 12% and 17% respectively. Itshould be noted that when sparged with air, the water may becomesaturated with oxygen, but it is unlikely that the water issuperoxygenated.

A. Superoxygenated Water in Hydroponic Culture.

Two small hydroponic systems were set up to grow two tomato plants.Circulation protocols were identical except that the 2 ½ gallon waterreservoir for the Control plant was eroated with and aquarium bubblerand that for the Test plant was oxygenated with a five-inch stripemitter for two minutes prior to pumping. The cycle was set at fourminutes of pumping, followed by four minutes of rest. The control waterhad an oxygen content of about 97% to 103% saturation, that is, it wassaturated with oxygen. The test water had an oxygen content of about153% to 165% saturation, that is, it was supersaturated. The test plantwas at least four times the volume of the control plant and began toshow what looked like fertilizer burn. At that point the fertilizer forthe Test plant was reduced by half. Since the plants were not exposed tonatural light but to continuous artificial light in an indoorenvironment without the natural means of fertilization (wind and/orinsects), the experiment was discontinued after three months. At thattime, the Test plant but not the Control plant had blossomed.

B. Superoxygenated Water in Field Culture.

A pilot study was designed to ascertain that plants outside thehydroponic culture facility would benefit from the application ofoxygen. It was decided to use water treated with the emitter of Example1 as the oxygen carrier. Since water so treated is supersaturated, it isan excellent carrier of oxygen.

Tomato seeds (Burpee “Big Boy”) were planted in one-inch diameter peatand dirt plugs encased in cheese cloth and placed in a tray in asouthwest window. Controls were watered once a day with tap water(“Control”) or oxygenated water (“Test”). Both Controls and Testsprouted at one week. After five weeks, the Test plants were an averageof 11 inches tall while the Controls were an average of nine inchestall. At this time, May 10, when the threat of frost in Minnesota wasminimal, the plants were transplanted to 13 inch diameter pots withdrainage holes. Four inches of top soil was added to each pot, toppedoff with four inches of Scott's Potting Soil. The pots were placedoutside in a sunny area with at least eight hours a day of full sun. Theplants were watered as needed with either plain tap water (Control) oroxygenated water (Test). The oxygenated water was produced by use of theemitter of Example 1 run for one-half hour in a five-gallon container ofwater. Previous experiments showed that water thus treated had an oxygencontent from 160% to 260% saturation. The Test plants flowered on June4, while the Controls did not flower until June 18. For both groups,every plant in the group first had flowers on the same day. All plantswere fertilized on July 2 and a soaker hose provided because the plantswere now so big that watering by hand was difficult. The soaker hose wasrun for one half to one hour each morning, depending on the weather, toa point at which the soil was saturated with water. One half hour afterthe soaker hose was turned off, about 750 ml of superoxygenated waterwas applied to each of the Test plants.

The Test plants were bushier than the Controls although the heights weresimilar. At this time, there were eight Control plants and seven Testplants because one of the Test plants broke in a storm. On July 2, thecontrol plants averaged about 17 primary branches from the vine stem,while the control plants averaged about 13 primary branches from thevine stem. As the tomatoes matured, each was weighed on a kitchen scaleat harvest. The yield history is shown in Table II.

TABLE II Control, grams Test, grams tomatoes from tomatoes from eightplants/ seven plants/ Week of: cumulative total cumulative total July 27240 400 August 3 180 420 2910 3310 August 10 905 1325 1830 5140 August17 410 1735 2590 7730 August 24 3300 5035 2470 10200 August 31 4150 91751580 11780 September 15 not weighed 3710 15490 Final Harvest 6435 156208895 24385 September 24

The total yield for the eight Control plants was 15620 grams or 1952grams of tomatoes per plant.

The total yield for the seven Test plants was 24385 grams or 3484 gramsof tomatoes per plant, an increase in yield of about 79% over theControl plants.

FIG. 6 shows the cumulative total as plotted against time. Not only didthe Test plants blossom and bear fruit earlier, but that the Controlplants never caught up to the test plants in the short Minnesota growingseason. It should be noted that the experiment was terminated because ofpredicted frost. All fruits, both green and red, were harvested andweighed at that point.

EXAMPLE 6 Flow-Through Emitter for Agricultural Use

In order to apply the findings of example 5 to agricultural uses, anemitter than can oxygenate running water efficiently was developed. InFIG. 7(A), the oxygenation chamber is comprised of three anodes 1 andcathodes 2, of appropriate size to fit inside a tube or hose andseparated by the critical distance are placed within a tube or hose 3 at120° angles to each other. The anodes and cathodes are positioned withstabilizing hardware 4. The stabilizing hardware, which can be anyconfiguration such as a screw, rod or washer, is preferably formed fromstainless steel. FIG. 7(B) shows a plan view of the oxygenation chamberwith stabilizing hardware 4 serving as a connector to the power sourceand stabilizing hardware 5 serving as a connector to the power source.The active area is shown at 6.

This invention is not limited to the design selected for thisembodiment. Those skilled in the art can readily fabricate any of theemitters shown in FIG. 4 or 5, or can design other embodiments that willoxygenate flowing water. One useful embodiment is the “T” model, whereinthe emitter unit is set in a side arm. The emitted bubbles are sweptinto the water flow. The unit is detachable for easy servicing. TableIII shows several models of flow through emitters. The voltage andflowrates were held constant and the current varied. The Dissolvedoxygen (DO) from the source was 7.1 mg/liter. The starting temperaturewas 12.2° C. but the flowing water cooled slightly to 11 or 11.5° C.Without undue experimentation, anyone may easily select the embodimentthat best suits desired characteristics from Table III or designed withthe teachings of Table III.

TABLE III ACTIVE DO OF* ELECTRODE CURRENT, FLOW RATE SAMPLE AT MODELAREA, SQ.IN. VOLTAGE AMPS. GAL/MINUTE ONE MINUTE 2-Inch “T” 2 28.3 0.7212 N/A 3-inch “T” 3 28.3 1.75 12 N/A 2-plate Tube 20 28.3 9.1 12 8.43-Plate tube 30 28.3 12.8 12 9.6 *As the apparatus runs longer, theflowing water becomes milky, indicating supersaturation. The one-minutetime point shows the rapid increase in oxygenation.

The following plants will be tested for response to superoxygenatedwater: grape vines, lettuce, and radishes in three different climatezones. The operators for these facilities will be supplied with unitsfor drip irrigation. Drip irrigation is a technique wherein water ispumped through a pipe or hose with perforations at the site of eachplant to be irrigated. The conduit may be underground or above ground.Since the water is applied directly to the plant rather than wetting theentire field, this technique is especially useful in arid climates orfor plants requiring high fertilizer applications.

The superoxygenated water will be applied by drip irrigation per theusual protocol for the respective plants. Growth and yield will becompared to the same plants given only the usual irrigation water. Pestcontrol and fertilization will be the same between test and controlplants, except that the operators of the experiments will be cautionedto be aware of the possibility of fertilizer burn in the test plants andto adjust their protocols accordingly.

It is expected that the superoxygenated plants with drip irrigation willshow more improved performance with more continuous application ofoxygen than did the tomato plants of Example 5, which were givensuperoxygenated water only once a day.

EXAMPLE 7 Treatment of Waste Water

Waste water, with a high organic content, has a high BOD, due to thebacterial flora. It is desirable to raise the oxygen content of thewaste water in order to cause the flora to flocculate. However, it isvery difficult to effectively oxygenate such water. Using a 4 inch OEM(see Table I) with a 12 volt battery, four liters of waste water in afive gallon pail were oxygenated. As shown in FIG. 8, the dissolvedoxygen went from 0.5 mg/l to 10.8 mg/l in nine minutes.

Those skilled in the art will readily comprehend that variations,modifications and additions may in the embodiments described herein maybe made. Therefore, such variations, modifications and additions arewithin the scope of the appended claims.

1. A method for treating waste water comprising; providing aflow-through oxygenator comprising an emitter for electrolyticgeneration of microbubbles of oxygen comprising an anode separated at acritical distance from a cathode and a power source all in electricalcommunication with each other, placing the emitter within a conduit; andpassing waste water through the conduit.
 2. An emitter for electrolyticgeneration of microbubbles of oxygen in an aqueous medium comprising: ananode separated at a critical distance from a cathode, a nonconductivespacer maintaining the separation of the anode and cathode, thenonconductive spacer having a spacer thickness between 0.005 to 0.050inches such that the critical distance is less than 0.060 inches and apower source all in electrical communication with each other, whereinthe critical distance results in the formation of oxygen bubbles havinga bubble diameter less than 0.0006 inches, said oxygen bubbles beingincapable of breading the surface tension of the aqueous medium suchthat said aqueous medium is supersaturated with oxygen.
 3. The emitterof claim 2, wherein the anode is a metal or a metallic oxide or acombination of a metal and a metallic oxide.
 4. The emitter of claim 2,wherein the anode is platinum and iridium oxide on a support.
 5. Theemitter of claim 2, wherein the cathode is a metal or metallic oxide ora combination of a metal and a metallic oxide.
 6. The emitter of claim2, wherein the critical distance is 0.005 to 0.060 inches.
 7. Theemitter of claim 2, comprising a plurality of anodes separated at thecritical distance from a plurality of cathodes.
 8. A method foroxygenating a non-native habitat for temporarily keeping aquaticanimals, comprising: inserting the emitter of claim 2 into the aqueousmedium, the non-native habitat comprising an aquarium, a bait bucket ora live well.
 9. A method for lowering the biologic oxygen demand ofpolluted water comprising: passing the polluted water through a vesselcontaining the emitter of claim
 2. 10. A supersaturated aqueous productformed with the emitter of claim 2, the supersaturated aqueous producthaving an approximately neutral pH.
 11. The emitter of claim 2, furthercomprising a timer control.
 12. The emitter of claim 2, wherein theanode and cathode are arranged such that the emitter assumes a funnel orpyramidal shaped emitter.